package open189.sign;

import java.net.URLEncoder;
import java.util.TreeMap;
import javax.crypto.Mac;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class ParamsSign
{
  private static char[] base64EncodeChars = { 
    'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 
    'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 
    'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 
    'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 
    'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 
    'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 
    'w', 'x', 'y', 'z', '0', '1', '2', '3', 
    '4', '5', '6', '7', '8', '9', '+', '/' };

  public static String value(TreeMap<String, String> params, String app_secret)
  {
    try
    {
      String signStr = "";
      for (String pName : params.keySet()) {
        signStr = signStr + "&" + pName + "=" + (String)params.get(pName);
      }
      byte[] hmacSHA1Bytes = hmacSHA1Encrypt(signStr.substring(1), app_secret);
      return URLEncoder.encode(encryptBASE64(hmacSHA1Bytes), "UTF-8");
    } catch (Exception e) {
      e.printStackTrace();
    }return "error";
  }

  private static byte[] hmacSHA1Encrypt(String encryptText, String encryptKey)
    throws Exception
  {
    String MAC_NAME = "HmacSHA1";
    String ENCODING = "UTF-8";
    byte[] data = encryptKey.getBytes(ENCODING);
    SecretKey secretKey = new SecretKeySpec(data, MAC_NAME);
    Mac mac = Mac.getInstance(MAC_NAME);
    mac.init(secretKey);
    byte[] text = encryptText.getBytes(ENCODING);
    return mac.doFinal(text);
  }

  private static String encryptBASE64(byte[] key)
    throws Exception
  {
    return new String(base64Encode(key));
  }

  private static String base64Encode(byte[] data)
  {
    StringBuffer sb = new StringBuffer();
    int len = data.length;
    int i = 0;

    while (i < len) {
      int b1 = data[(i++)] & 0xFF;
      if (i == len) {
        sb.append(base64EncodeChars[(b1 >>> 2)]);
        sb.append(base64EncodeChars[((b1 & 0x3) << 4)]);
        sb.append("==");
        break;
      }
      int b2 = data[(i++)] & 0xFF;
      if (i == len) {
        sb.append(base64EncodeChars[(b1 >>> 2)]);
        sb.append(base64EncodeChars[((b1 & 0x3) << 4 | (b2 & 0xF0) >>> 4)]);
        sb.append(base64EncodeChars[((b2 & 0xF) << 2)]);
        sb.append("=");
        break;
      }
      int b3 = data[(i++)] & 0xFF;
      sb.append(base64EncodeChars[(b1 >>> 2)]);
      sb.append(base64EncodeChars[((b1 & 0x3) << 4 | (b2 & 0xF0) >>> 4)]);
      sb.append(base64EncodeChars[((b2 & 0xF) << 2 | (b3 & 0xC0) >>> 6)]);
      sb.append(base64EncodeChars[(b3 & 0x3F)]);
    }
    return sb.toString();
  }
}